Left turn signal and Brake Lights, Don't Work!

[Mannix]

Hey guys been here for a year, but still in the newbie range (I'm wrenchy but could use suggestions for a book that breaks down motorcycle mechanics and maintenance?).

My '83 XS400 has a few issues I need to look into, but most pressing right now is electrical. I've recently noticed that the brake lights don't fire. Also, on my left turn signal only the front light goes on and it doesn't blink. Then, occasionally, and less recently, the headlight will cut out and I'll have to turn her off and re-start to get power back. I changed the battery last year and noticed some odd power fluctuations, but these new problems are fairly recent. I checked all the bulbs and fuses and except for one coil they are all still good. I'm not really sure where to start. I'm happy to open her up and start tracking paths of wires but figured I'd see what the XS400 Genius Bar could offer

 

[Edward]

Is it the stock fuse box? I know you said the fuses look good, but I'd definitely double check that all the fuses are still making contact with the contacts. Rotate them around a little to break through the crud. Or even better, check that there's power at each one with a multimeter. Same thing with the bulbs, pull them out and clean out all the sockets.

Also, I would double check that the tail lights don't have the brake lights always on. For some reason, my bike's PO disconnected the rear brake switch and just shorted the wires together, permanently turning on the brake lights.

If that doesn't help, check to make sure that all the brake switches are getting power and are switching on and off properly. Take your multimeter and connect the ground somewhere and poke around at the connections to measure the 12V.

As for the blinker, when you switch it to the turn signal, do you hear any clicking at all? Without looking at the wiring diagram, I would think that the front and rear blinkers are connected in parallel, if the front turns on, the rear should as well. Hopefully the bulb socket cleaning will get that working. You can unplug the flasher relay and take a piece of wire to jump it to see if you can get the lights to work. A replacement flasher relay is easy to get at the auto store.

 

[willem]

your left rear blinker not working is the cause for your left front blinker not blinking. Your relay needs a certain load to function, and if your rear blinker isn't pulling any load your relay won't go on. Try to put the bulb from another blinker in the rear left one, to rule out the bulb. Then I would look into the socket for the rear left blinker, make sure there's no corrosion there. If you're sure there's a good connection, trace the wires back all the way to find where it's going wrong. Inside switches are also places corrosion occurs more easily.

That's also where I'd start looking for problems with the headlight, after you've ruled out the fuse box (I agree with edward on that one ) The high-low beam switch is likely to be corroded, or the light on/off switch on the right side of your handlebars.

Brake light, as edward says. I had some problems with it as well, and it turned out to be the socket in the taillight not connecting with the bulbs (I have an aftermarket double tail light).

I really don't like electrics, but you'll have to keep a cool head and trace your issues. Odd power fluctuations are never good, and you should investigate these asap. Make sure your main switch (the keyhole) is good, that's a big one of course. Go through some threads on electrics here on the forum and measure your charging system. And just have a good look at all your connectors and wires under the seat and tank. Repair anything that looks suspicious, and do it properly. That means soldering and shrink tubing, not glue and electrical tape

 

[Mannix]

Thanks guys, you've given me some great places to start. I've got my voltmeter coming so that should help with some of the component troubleshooting. I'll let you know how it goes when I find some work time!